The invention relates to a sealing arrangement for a microwave oven having an oven cavity with an access opening closable by a door. The sealing arrangement comprises an attenuation choke which extends around the access opening at least when the door is closed, and which is arranged either in wall portions of the cavity surrounding the access opening or in rim portions of the door. The choke has an input opening adjacent a gap leading from the oven cavity past the input opening to the space outside the cavity and also has a short-circuiting wall situated at a distance of approximately 1/2 wavelength at the operating frequency from the inner end of the gap at the cavity, and which is provided with transverse slots in a wall thereof.
Choke arrangements comprising slotted walls have previously been proposed as sealing devices in microwave ovens. Such slots in a choke wall prevent the generation of higher oscillation modes in the elongated attenuation chokes and will thereby decrease the quantity of leaking energy. A type of slotted choke for microwave ovens is for example described in U.S. Pat. No. 3,767,884. Here the slots are situated in a choke side wall, which at the same time forms a separation wall betwee the choke space and an input gap leading from the oven cavity to the input opening of the choke. Another type of choke having a slotted wall is described in United Kingdom Pat. No. 1,392,498. In this case the choke space is divided into two sub-spaces by a slotted partition wall. Both sub-spaces are open towards the gap formed between the cavity walls surrounding the access opening and the door, which gap forms a transmission path for the leakage energy. Each such sub-space serves as a choke and the arrangement can be regarded as two complete chokes arranged in sequence in the propagation path for the leakage energy. As it is the common partition wall for these two sub-spaces that is slotted, both these chokes comprise a slotted wall.